At some point, everyone has experienced a temporary groggy feeling after waking up called sleep inertia. Scientists know a lot about sleep inertia already, including how it impairs cognitive and motor abilities, and how it varies with the time of day and type of sleep that precedes it. They even have pictures of how the brain wakes up piece by piece.
People with idiopathic hypersomnia or IH display something that seems stronger, termed “sleep drunkenness,” which can last for hours. Czech neurologist Bedrich Roth, the first to identify IH as something separate from other sleep disorders, proposed sleep drunkenness as IH’s defining characteristic.
Note: Emory readers may recall the young Atlanta lawyer treated for IH by David Rye, Kathy Parker and colleagues several years ago. Our post today is part of IH Awareness Week® 2017.
Sleep drunkenness is what makes IH distinctive in comparison to narcolepsy, especially narcolepsy with cataplexy, whose sufferers tend to fall asleep quickly. Those with full body cataplexy can collapse on the floor in response to emotions such as surprise or amusement. In contrast, people with IH tend not to doze off so suddenly, but they do identify with the statement “Waking up is the hardest thing I do all day.”
At Emory, neurologist Lynn Marie Trotti and colleagues are in the middle of a brain imaging study looking at sleep drunkenness.
“We want to find out if sleep drunkenness in IH is the same as what happens to healthy people with sleep inertia and is more pronounced, or whether it’s something different,” Trotti says. Read more
Neuroscientists at Emory have refined a map showing which parts of the brain are activated during head rotation, resolving a decades-old puzzle. Their findings may help in the study of movement disorders affecting the head and neck, such as cervical dystonia and head tremor.
The results were published inÂ Journal of Neuroscience.
In landmark experiments published in the 1940s and 50s, Canadian neurosurgeon Wilder Penfield and colleagues determined which parts of the motor cortex controlled the movements of which parts of the body.
Penfield stimulated the brain with electricity in patients undergoing epilepsy surgery, and used the results to draw a â€œmotor homunculusâ€: a distorted representation of the human body within the brain. Penfield assigned control of the neck muscles to a region between those that control the fingers and face, a finding inconsistent with some studies that came later.
Using modern functional MRI (magnetic resonance imaging), researchers at Emory University School of Medicine have shown that the neckâ€™s motor control region in the brain is actually between the shoulders and trunk, a location that more closely matches the arrangement of the body itself.
â€œWe canâ€™t be that hard on Penfield, because the number of cases where he was able to study head movement was quite limited, and studying head motion as he did, by applying an electrode directly to the brain, creates some challenges,â€ says lead author Buz Jinnah, MD, professor of neurology, human genetics and pediatrics at Emory University School of Medicine. Read more